MIC4833
Low Noise Dual 220 VPP EL Driver
With Output Voltage Slew Rate Control
General Description
Features
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Drives two EL panels, up to 4 in2 each at full
brightness
The MIC4833 is a low noise dual Electroluminescent (EL)
Panel driver used in backlighting applications. The
MIC4833 converts a low DC voltage to a high DC voltage
using a boost converter and then alternates the high DC
voltage across the EL panels using an H-bridge. The
MIC4833 incorporates internal wave-shaping circuitry
specifically designed to reduce audible noise emitted by
EL panels. The two EL panels may be dimmed by applying
a PWM signal to the device. The MIC4833 drives two
outputs from a single inductor and requires a minimum
number of passive components. It features an operating
input voltage range of 2.3V to 5.8V, making it suitable for
1-cell Li-ion and 2- or 3-cell alkaline/NiCad/NiMH battery
applications.
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Independent input control for each of the two panels
and allows PWM dimming.
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220Vpp regulated AC output waveform
2.3V to 5.8V DC input voltage
Wave-shaping circuit to reduce audible noise
Adjustable slew rate for audible noise reduction
Independently adjustable boost converter and EL
panel frequency
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Single inductor to power both panels
0.1uA typical shutdown current
12 pin 3mmx3mm MLF® package
–40oC to +125oC junction temperature range
An external resistor may be used to adjust the output
voltage slew rate to reduce audible noise. The MIC4833
features separate oscillators for the boost and H-bridge
stages to allow independent control. External resistors set
the operating frequencies of each stage allowing the EL
circuit to optimize efficiency and brightness.
Applications
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Mobile Phones
MP3s/Portable Media Players (PMP)
Clocks/ Watches
Remote Controls
Cordless Phones
GPS Devices
The MIC4833 is available in a 12 pin 3mmx3mm MLF®
package, and has an operating junction temperature range
of –40°C to +125°C.
PDAs
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Typical Application
High
50k
Low
ENA
VDD
RSW
REL
ENB
GND
SLEW
ELA
ELB
COM
CS
VIN
Li Ion
3V to 4.2V
EL Lamp A
EL Lamp B
332k
0.01µF
MIC4833
1.78M
High
High
Low
Low
SW
VIN
Li Ion
3V to 4.2V
220µH
2.2nF
250V
10µF
Low Noise Dual EL Driver
MLF and MicroLead Frame are registered trademark of Amkor Technologies
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-100308
(408) 955-1690
October 2008